Supernova model discrimination with a kilotonne-scale Gd-H$_{2}$O Cherenkov detector

TL;DR

This study assesses the ability of a kilotonne-scale Gd-H$_{2}$O Cherenkov detector to distinguish between different supernova models using antineutrino spectra, demonstrating high discrimination accuracy and early warning potential.

Contribution

It introduces a detailed analysis of supernova model discrimination capabilities of a proposed large-scale water Cherenkov detector, highlighting the importance of detector size and configuration.

Findings

Detector can distinguish supernova models with over 90% accuracy.

Larger detector tanks maintain discrimination performance at greater distances.

The detector can provide early supernova warnings for the entire Milky Way.

Abstract

The supernova model discrimination capabilities of the WATCHMAN detector concept are explored. This cylindrical kilotonne-scale water Cherenkov detector design has been developed to detect reactor antineutrinos through inverse $\beta$-decay for non-proliferation applications but also has the ability to observe antineutrino bursts of core-collapse supernovae within our galaxy. Detector configurations with sizes ranging from 16 m to 22 m tank diameter and 10% to 20% PMT coverage are used to compare the expected observable antineutrino spectra based on the Nakazato, Vartanyan and Warren supernova models. These spectra are then compared to each other with a fixed event count of 100 observed inverse $\beta$-decay events and a benchmark supernova at 10 kpc distance from Earth. By comparing the expected spectra, each detector configuration's ability to distinguish is evaluated. This analysis then demonstrates that the detector design is capable of meaningful event discrimination (90+% accuracy) with 100 observed supernova antineutrino events in most configurations. Furthermore, a larger tank configuration can maintain this performance at 10 kpc distance and above, indicating that overall target mass is the main factor for such a detector's discrimination capabilities. Finally, it is estimated that the detector design can provide early warning capability for supernova bursts for the entire Milky Way in all configurations.